Grab for lifting hollow objects



Feb. 18, 1958 K. w. HORTON 48 GRAB FOR LIFTING HOLLOW OBJECTS Filed Dec. 21, 1955 2 Sheets-Sheet 1 INVENTOR.

H KEnneih W. Hm P1 1311 K. W. HORTON GRAB FOR LIFTING HOLLQW OBJECTS Feb. 18, 1958 2 Sheets-Sheet 2 Filed Dec. 21, 1955 n R 0W 0 r H 5 m a m w ,fl m M a m w M n Y M mm W WI 8 8 I 6 Q m 6 .1/ m ul/lu 6 M. 9 9 2 3 2 5 H n M w z w Q m M a 3 United States Patent 2,823,948 GRAB FOR LIFT-INC HOLLOW OBJECTS Kenneth W. Horton, Watervliet, N. Y. Application December 21, 1955, Serial No. 554,596

2 Claims. Cl. 294-91 (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to lifting devices and more particularly to a grab which grips a load by frictional means.

It is an object of this invention to provide a grab for lifting hollow objects by frictional means.

- It is another object of this invention to provide a grab forlifting hollow objects where the size and surface character of the interior progressively change.

. It is a further object of this invention to provide a grab having a pair of internally expanding jaws which are actuata'ble to resiliently and frictionally grip the interior surface of a hollow object by the weight of such object.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawingsin which:

Fig. 1 is, a partially cross-sectional side view of the grab locked in unloaded condition showing the arrangement of the lever mechanism;

Fig. 2 is a view taken along line 2-2 of Fig. 1;

Fig. 3 is a view taken along line 3-3 of Fig. 1; and

Fig. 4 is a partially cross-sectional side view showing the grab lifting a hollow cylinder.

Shown in the Figs. is a grab 12 having a pair of substantially rectangular side plates 14 which are secured in spaced apart position by four stud bolts 16 which are mounted through such side plates at each corner. Each of the stud bolts 16 is provided with a cylindrical body portion 18, which acts as a bearing for a member pivotally mounted thereon as hereinafter noted, and a threaded portion 20 at each end. Threaded portions 20 are of smaller diameter than body portion 18 and extend from shoulders 22 formed at the junctions thereof with such body portion through suitable holes 24 in side plates 14. Nuts 25, threadably mounted on threaded portion 20, press side plates 14 against shoulders 22 thereby fixedly securing such plates in position.

An elongated bell crank lever 26 is pivotally mounted on the body portion 18 of each of the two stud bolts 16 mounted through the bottom sides of side plates 14 by means of a cylindrical hole 28 through the lower portion of one end of such lever. Bell crank levers 26 are so mounted that the free ends 29 thereof extend toward each other and are of such length that such free ends are spaced apart when such levers are longitudinally aligned. Provided transversely through each of the bell crank levers 26 above hole 28 is a bore 30 which receives a pin 32 upon which there is pivotally mounted, as hereinafter described, a jaw member 34. Whereby, rotation of the free ends 29 upwardly causes the jaw member 34 to be moved outwardly.

Each of the jaw members 34 is comprised of a saddle portion 36 which is received between side plates 14 and a rectangular shoe portion 38 which is symmetrically mounted to one end of such saddle portion outside of side plates 14 and is engageable with the inside surface of a hollow object such as cylinder 39. The free ends of each of the saddle portions 36 are bifurcated to receive ends 29 of the bell crank levers 26 and a hole 42 is provided in each of such bifurcated portions to rotatably receive the pin 32. Shoe portions 38 are fabricated from spring steel and each is provided with an arcuate face portion 44 which is contactable with the inside surface of cylinder 39. Each of the face portions 44 is lined with a material 46, such as brake lining, which has a high frictional coefliciency to frictionally grip the inside surfaces of the object to be lifted. The face portions 44 have a larger radius than that of the inside surface of cylinder 39 or, if such grab is to be used for lifting hollow objects in which the inside surfaces are straight, has a slightly concave contour. Whereby, when the jaw members 34 are pressed against the inside surfaces of the object to be lifted, the segmental ends of the lining 46 on the face portions 44 contact such inside surface first with such shoe springing inwardly for full circumferential contact of the lined face portions with the inside surface when pressure is applied by such jaw members. As jaw members 34 are pivotally mounted to bell crank levers 26, they are self-centering when actuated against the interior surface of cylinder 39 and thereby the wear of lining 46 is reduced.

An arm 48 is mounted at one end to the stud bolt 16 which is mounted through the top right corner of the side plates 14. A pair of arms 50, similar to arm 48 but onehalf as thick, are pivotally mounted in juxtaposition on the stud bolt 16 which is mounted through the top left corner of the side plates 14. Arm 48 is arranged to cross between the pair of arms 50 with the free ends of such arms 48 and 50 extending beyond the side plates 14. One end of a bar 52 is received between the free ends of the arms 50 and is hingedly connected thereto by a bolt 54. A pair of identical bars 56 is juxtaposed on opposite sides of bar 52 with one end of such bars being hingedly joined to the free end of arm 48 by a bolt 58. The free ends of bars 56 and bar 52 meet a distance above side plates 14 when arms 48 and 50 are longitudinally aligned and are hingedly joined by a pin 60.

The left one of the bell crank levers 26 is connected to the arms 50 by means of a link 62 which is bifurcated at one end to receive end 29 of such bell crank lever and is reduced in cross section at the opposite end so as to be received by such arms. A cylindrical hole 64 transverses link 62 and bell crank lever 26 to provide a mounting hole for a pin 65. Link 62 is hingedly connected by a pin 67 to arms 50 at approximately the same distance from the top left one of the stud bolts 16 as pin 65 is from the bottom left one of the stud bolts 16.

The right one of the bell crank levers 26 is connected to arm 48 by means of a link 66 which is bifurcated at one end to receive end 29 of such bell crank lever and at the opposite end to receive arm 48. Link 66 is hingedly mounted to the right one of bell crank levers 26 by means of a transverse pin 68 and to arm 48 by a pin 69 at approximately the same distance from the top rightv one of the stud bolts 16 as pin 68 is from the bottom right one of the stud bolts 16.

Also mounted to pin 60 is a yoke 70 which is engageable by a lifting device (not shown), such as a hoist, and a pair of hooks 72 which are pivotally mounted on each end of such pin. Each one of the books 72 is engageable with a lug 74 extending from the adjacent side plate 14 when arms 48 and 50 are longitudinally aligned. Whereby, the jaw members 34 are retracted toward each other while grab 12 is being transported, ready for insertion into cylinder 39.

Lips 76 extend from the right and left sides of the uppermost portion of side plates 14 to engage the upper side of cylinder 39 and rest thereon while books 72 are disengaged from lugs 74. Lips 76 thereby limit entrance of grab 12 into the interior of cylinder 39.

When grab 12 is in place with lips 76 resting on the top of cylinder 39 and books 72 disengaged from lugs 74, and the lifting device is actuated upwardly, the upward lift on yoke 70 against the weight of the grab causes bars 52 and 56 and the pivotally connected arms 48 and 50 to straighten out vertically. As 'arms 48 and 50 are rotated towards a vertical position, the jaw members 34 pivotally mounted thereto are moved laterally outward into contact with the interior surface of cylinder 39. I

It will be noted, referring to Figs. 1 and 2, that in respect to arms 50, the distance between the mounting stud bolt 16 and pin 67 is shorter than that betweensuch stud bolt and pin 54 and that, in respect to arm 48, the distance between the mounting stud bolt and pin 69 is shorter than that between such stud bolt and pin for a mechanical advantage. Also, in respect to the bell crank levers 26 the distance between the-mounting stud bolts 16 therefor and the pins 32 is less than that between such stud bolts and the pins 65 and 6 8 forla dditional mechanical advantage. Whereby, the force with which jaw members 34 press against the interior surface of cylinder 39 is increased many times over that exerted upwardly against arms 48 and 50 so that the force pr the weight .of such cylinder is, while being lifted, multiplied several times and such increased force translated ,to' lateral pressure of such jaw members against ithe interior of cylinder 39. The lining material 46 on face portions 44 assures nonslipping contact between grab gland cylinder 39. l

It is obvious that by being flexible shoe portions 3,8 are adaptable to variations in the character of the contacting surface. Also, that the combined lateral :rn oyements of jaw members 34 make grab 12 adaptable to interior holes of various diameters. This is advantageous when grab 12 is used to transport in a production line a heavy hollow object wherein the interior surface pi gressively changes from a rough to asmooth stateand wherein the diameter of the interior hole progressively increases. 7 i j From the foregoing, it is clearly apparent that there is herein provided a grab for lifting hollow obj ectswh ich is rugged in construction, simple ,in operation and is adaptable to lifting hollow objects of changing interrior dimensions andlsurface characteristics.

Although aparticularembodiment of th invention has been described in detail herein, it is evident that many variations may be devised within the and scope thereof and the following claims are intended to ,include such variations.

I claim:

1. For a lifting device, .a grab for releasably gripping the inside of a hollowobject to be hoisted including 'apair of rectangular sideplates vertically insertable intoIth object and being fixedly joined in spaced lateral juxtaposition by stud bolts mounted between each of the top corners and each of the bottom corners of said sideplates, lips e l tending outwardly from said top corners for engagement with the top of the object for limitingentrance .of saidgra'b thereinto, a bell crank lever pivotallyrnounted pnseaehfof said stud bolts mounted .oe tween saidbo ttorn corners, a jaw member pivotally mounted for ,a n echaniealadyantage to one end of each one of said bell crank levers for actuation thereby against the inside of the object with a force greater than that applied to said bell crank lever, a resilient shoe portion on each of said jaw members, a lined face portion on each of said shoe portions resiliently and frictionally engageable with the inside of the object when actuated thereagainst by said bell crank levers, and lever means engageable by the lifting device for hoisting said grab, said lever means being pivotally mounted to said bell crank levers for simultaneous actuation of said jaw members against the inside of the object with a greater force than that applied by the lifting device to said lever means when hoisting said grab.

2. For alifting device, a grab for releasably gripping the inside of a hollow object to be hoisted including a pair of rectangular side plates insertable vertically into the object and being fixedly'joined in spaced lateral juxtaposition by stud bolts mounted betweeneach of the top corners and each of the bottom corners of said side plates, lips extending outwardly from said top corners for eng'agement'with the top of the object for limiting entrance of said grab thereinto, a bell crank lever pivotally mounted on each of said stud bolts mounted between said bottom corners, a jaw member pivotally mounted for a mechanical advantage to oneien'cl of each one of said bell crank'leve'rs for actuation thereby against the inside of the object with a force greater than that applied to said bell crank levers, a resilient shoe portion on .each of said jaw members, a lined face portion on each of said shoe portions resiliently and frictionally engageable with the inside of the object when actuated thereagainst by said bell crank levers, an arm pivotally mounted on each of said stud bolts mounted between said top corners and disposed in cross relationship so that the free ends thereof are adjacent the opposite ones of said top corners, a bar pivotally mounted at one end to said free end of each one of said arms and at the opposite end to the other one of said bars by means of a pin, a link pivotallyrnounted at one end to the free end of each one of said bell crank levers and pivotally mounted at the opposite end to the adjacent one of said arms so that said arms apply a greater force to said links than is applied thereto,'a yoke pivotally mounted on said pin and being engageable by .the lifting device for hoisting said grab, and hook means pivotally mounted on said pin for releasable engagement with lug means on said side plates for releasably locking said jaws in contracted positions'for insertion into the hollow object when saidgrab is transported by the lifting device.

References flited in the file of this .patent UNITED STATES PATENTS 

